The way block availability is now, I think the conversion kit is a viable option. If I was in the market, I'd definitely be looking into it.

Anyone remember Steve Magnante's (from Hot Rod magazine, B-J Auction, etc.) red hemi dart? That was a Stage V conversion on a 440 block if I'm not mistaken.

Lets be honest here...most people building a hemi aren't looking to make block breaking power. Less than 600 hp is what most seem to be after and a stock block will last a long time doing that.